Automatic choke control



March "27 192% L. B. READ AUTOMATIC CHOKE comm;

2 Sheets-Sheet 1 Filed GOV, 11, 1945 INVENTOR. LELAND B. READ I I z ATTORNEY FIG.2.

March 7 195%? L. a. READ AUTOMATIC snows, QONTROL,

2 Sheei;s-Sheei. 2

Filed. 00 11,, 1945 INVENTOR. LELAND B. READ ATTORNEY Patented Mar. 7, 1950 UNITED STATES PATENT OFFICE AUTOMATIC CHOKE CONTROL Leland B. Read, St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application October 11, 1945, Serial No. 621,727

9 Claims.

that when the choke valve is closed, the cam is positively moved to its fast idle position. However, if the throttle valve is closed with the choke valve in its wide open position, the cam interferes with closing of the choke valve thereafter so that it is necessary to partially open the throttle valve to release the cam before the choke can be closed for cold starting. Where the choke is controlled by a thermostat, this results in the thermostat being maintained, perhaps. for long periods, under greater tension than necessary after the vehicle is stopped and the thermostat allowed to cool.

It is an object of the present invention to operatively connect the choke valve and the fast idle member in such a way that the choke valve can close even though the movement of the fast idle member is restricted by the throttle screw.

Another object is to operatively connect the choke valve and fast idle member so that the choke can move fully in either direction irrespective of the position of the fast idle member and throttle valve.

Still another object is to operatively connect the choke valve and the fast idle member by means of a light spring which will hold the fast idle member properly when rel-eased by the throttle screw, and which may be stressed to permit full movement of the choke valve in either direction irrespective of the positionof the fast idle member or throttle screw. I

These objects and other more detailed objects hereafter appearing are attained by the device illustrated in the accompanying drawings in which Fig. 1 is a vertical transverse section illustrating a portion of an engine induction conduit embody.- ing the invention.

Fig. 2 is a horizontal section of a substantially on line 2-2 of Fig. 1.

Fig. 3 is a side view showing the interconnection mechanism with the parts in the fast idle position, the outer portion of the housing being removed.

Fig. 4 shows a part of the structure in Fig. 3, but with the choke valve fully opened.

Fig. 5 is a View similar to Fig. 3, but, showing detail taken 4 the housing in section and the parts in the normal idling position.

Fig. fishows a portion of the structure in Fig. 5, but with the choke valve fully closed.

Fig. 7 is a view similar to Fig. 5, but showing the parts in the unloading position.

Fig. 8 is a side view of the structure in Fig. 4.

Fig. 1 shows a portion of an internal combustion engine induction conduit including a downdraft mixture conduit l0 mounted on the intake manifold ll. The entry of air to the upper end of the conduit is controlled by a choke valve I2 mounted off center on a shaft I3. The supply of mixture to the engine is' controlled by a throttle valve [4 attached to a shaft 15, shafts l3 and being journalled in the walls of the conduit. The right hand end of the throttle shaft projects beyond the conduit and is provided with an arm [6 rigidly attached thereto and having'an aperture in its extremity H for attachment of throttle control mechanism extending to the drivers compartment.

Choke shaft l3 extends rightwardly into the automatic choke housing including an inner part l8 and an outer or cover part [9, separated by a plate 20. A coiled bi-metal thermostat 2i has its inner end anchored to a clip 22 projecting inwardly from portion IQ of the casing. The outer end of the thermostat is hooked about an L-shaped finger 23 projecting from a disk 24 rigidly attached to choke shaft [3. This disk has additional radial extensions 25 and 25a. Extension 25 is connected by a link 26 to a piston 21 working in a cylinder 28. The lower end of the cylinder is connected by a passage 29 to a port 30 opening into the induction conduit posterior to the throttle valve. Thermostat 2| and piston 21 cooperate to control the choke valve for cold starting and warm-up of the engine in the manner described in Coffey Patent No. 2,085,351 assigned to the assignee of the present invention.

Loosely received on the right hand end of choke shaft l3 (Fig. 1) and best shown in Figs. 3-8, is a cam having a high point 36 and a low point 31. which normally lies directly behind extension 25a on the disk 24,. A spiral spring (Fig. 8) is enforce movement of the cam with disk 24 and The cam has a radial extension 38 3 the choke valve when the movement of the cam is not interfered with.

A lever 45 is pivoted at one side of inner housing part I8 and has a pair of inwardly projecting fingers 46 and 47, inner finger 46 underlying cam 35 for engaging high point 36 or low point 31, according tothe position of the cam. The other finger 47 extends across a'vertical link 48 which is slidable in a closely fitting recess in the bottom of housing portion [8. Link 48 has spaced shoulders 49 and 50, respectively, ,be,low and above finger 4'! for cooperation tlie'r'ewith.- At its lower extremity, link 48 .isipivotallycon nected to a second link which, in turnfis con nected at its lower end to throttle arm 16. The lost motion interconnection is such that opening and closing of the throttle valve causes longitudinal movement of link 48 to bring shoulders 49 and 50 selectively into engagement with finger 41 on lever 45 and, correspondingly, rotate this lever about its pivot. M 1

When the choke valve is closed, as in,Fig. .3, high point 36 on the cam is in position to be en. gaged by finger 46 when thethrottle valveis moved towards closed position to limitthis movement to the fast idle position, as shown in Fig. 3. Onthe other hand, when the chokelvalve has been fully opened,,as .in .Fig. 4, low.point. 31 of the..cam.is abreast, fingerfitand Dermitsfurther. closing of the .throttlevalve to its normal. idling. position. Disk 24has a smalloutstanding finger-55 which is engaged by a, curved armjfi, on lever 45 when the throttle valve is fully opened, as shownin Fig. 7, to urge disk 24 clock wise and partially open the chckevalve against thejthermostatfor funloading excess fuel wh ich maybe trapped-in the manifoldi yari-ous fe f-. tures of the above descri red' interconnection? structure areshown and claimed inacoapending application Serial No. 464,643 filed November ',1 5, 1942, now Patent No. 1402.361. in theiname of, George M. Bcknell and assigned to the'as signee of the present application. I

When the cam is held in the fast idle position bythrottle controlled finger 46, as in Fig. 3, opening forces applied to the choke by the direct action of suction there n and alsqby the action of suction on piston 21 cause disk finger 25a to rotate clockwise relative to the .cam, calfryir' g spring extremity 42 with it and stressing the sprin (Fig. 4). On tbe other ha-nd, when ..the throttle is closed after the choke ha's been fully opened as in Fig. 5, throttlecontrol finger-.45" holds the cam in its normal idle position. Then, as the thermostat becomes cool urging the choke valve closed, disk finger 25a is rotated .counter clockwise relat ve to thecam, carrying the opposite spring extremity 43 with it and partially stressing the spring (Fig. 6). Spring40Iisjust strong enough to carry cam withdisk 24 when finger 46 does not interfere with the cam move ment. Consequently, the added resistance. of spring to choke movement, when th'eucamisi locked, is relatively light. The resilient connection formed by spring 40 is such that thechoke can move fully from its closed to its open posi; tion, as in Figs. 3 an d .4. orfronr its opentolit's closed position, as in Figs. 5 and 6,. irrespective of the position of the. cam and throttle valve. In the first case, the unbalanced choke valv e'is per mitted to breathe or yield as. far as necessary under the effect of air flow and suction thereon, In the latter case, the choke valveispermitted' to fully close asthe thermostat cools sofU ht th'g-i tension on and straining 6f the thermostat mixture should be too lean for continued running.., This results because such a lean mixture would cause slowing down of the engine to consequent reduction in manifold vacuum and air flow which tend tohold the choke open.

A. further advantage results in case the fast idle cam is locked with the choke partially open. Thisfrequently' causes the carburetor to supply a too lean mixture for continued running where the choke is also looked. By the use of the presentinvention, the slowing down of the engine andloss of manifold suction caused by leanness ofthe mixture are accompanied by additional closing of the choke under the influence of t e thermostat tocorrect for the excessive leanness.

Various features of the inventon may be modified as, will occur to th se skilled in the art and the. exclusive use .of all .modifications as come within the scope of the appended claims is contemplated In combination with an internal combustion. engine inductfon conduit having chok and throttle'valves therein, first and second e ements movablejrespectively, with said c ke valve and saidthrottle valve. and a member having a twowayyielding connection to'said first element and eng'ageahle by said second eler ent to ariably limitthe closing movement o said throttle valve in, accor'dance w th" the position of sad choke valve. said connection permitting full m vement of said choke in either direction irre pective of the position of said second element and said member.

2. In combinaton with an internal combustion engine induction c nduit having choke and throttle valves therein, first and second elements movable, respectively. with said chokevalve and said throttle valve and a fast idle member having a two-way, resilient connection to said first element and engageable by said second ele ent to restrict the closing movement of sad throttle when the choke valve is c osed. sai'i resilient connection permtting full movement of said choke valve'in either direction irrespective of the position of said throttle valve or said fast idle member.

3. In combination with an internal combustion engine induction conduit having choke and throttle valves therein, an arm rigidly connected I to and movable with said choke valve, a second arm connected to and movable with said throttle valve, a fast idle abutment on said second arm, and a fast idle member having a two-way, resilient connection to said first arm and engageable by said second arm to variably restrict the closing movementof said throttle valve in accordance with the position of said choke valve, said resilient connection permitting full movement of said choke valve in either, direction irrespective of the position of said throttle valve or said fast idle member.

4. In combination with an internal combustion engine induction conduit having choke and throttle valves therein, first and second arms rig idly' connected to and movable, respectively, with said choke valve and said throttle valve, a pivoted member engageable by said second arm when said chok valve is closed to restrict the closing movement of said throttle valve, and a two-way, resilient connection between said pivoted member and said choke valve adapted to permit full movement of said choke in either direction irrespective of the positions of said pivoted member and said second arm.

5. In combination with an internal combustion engine induction conduit having choke and throttle valves therein, first and second arms movable, respectively, with said choke valve and said throttle valve, a fast idle cam mounted adjacent said second arm and engageable thereby to limit the closing movement of said throttle to a fast idle position when said choke valve is closed, and a two-way, resilient connection between said cam and said first arm adapted to permit full movement of said choke valve in either direction irrespective of the position of said cam and said throttle arm.

6. In combination with an internal combustion engine induction conduit having choke and throttle valves therein, first and second arms movable, respectively, with said choke valve and said throttle valve, a fast idle cam mounted adjacent said choke arm, and having a two Way resilient connection to said choke arm, a device extending from said throttle arm for engaging said cam when said choke valve is in closed position to limit the closing movement of said throttle valve to its fast idle position, and structure on said choke arm engageable by said device when said throttle valve is fully opened to open said choke valve.

7. In combination with an internal combustion engine induction conduit having choke and throttle valves therein, means to resiliently close said choke valve for cold starting, members movable respectively with said choke valve and said throttle valve, a fast idle device mounted adjacent said throttle member and engageable thereby When said choke valve is closed to restrict the closing movement of said throttle valve, said device having a full two way resilient connection to said choke member, and structure on said device engageable by said choke member when said throttle valve is fully opened to partially open said choke valve against said resilient closing means. 7

8. A fast idle device for an internal combustion engine having an induction conduit with choke and throttle valves comprising elements movable, respectively, with said valves, a fast idle member movably mounted adjacent said choke valve element, said member and said choke valve element having extensions normally in close juxtaposition, and a spring having portions hooked about and embracing opposite sides of said extensions whereby said choke valve element may yield in opposite directions relative to said member by selective displacement of said spring portions and stressing of said spring.

9. A fast idle mecchanism for an internal combustion engine induction conduit having choke and throttle valves comprising an element rotatable with said choke valve, a second element movable with said throttle valve, and a fast idle cam pivotally mounted co-axially with said choke element, said cam being engageable by said throttle element to variably restrict the closing movement of said throttle, said choke element and said cam having radial extensions one normally overlying the other, and a spring having extremities hooked about and embracing opposite sides of said extensions whereby said choke element and choke valve may yield in either direction relative to said cam, when said cam is locked by said throttle element, by displacement of said spring extremities and stressing of said spring. v

LELAND B. READ.

REFERENCES crrsn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,143,153 Hunt Jan. 10, 1939 2,402,361 Bicknell June 18, 1946 

